High-speed printer employing a gas discharge matrix



United States Patent Charles D. Hendricks, Jr.

Chestnut Hill, Massachusetts [21 Appl. No. 724,499

[22] Filed April 26, 1968 [45] Patented Dec. 8, 1970 [73] Assignee Massachusetts Institute of Technology Cambridge, Massachusetts a corporation of Massachusetts [72] inventor [54] HIGH-SPEED PRINTER EMPLOYING A GAS Primary Examiner- Edgar S. Burr DISCHARGE MATRIX Attorneys -Thomas Cooch, Martin M. Santa and Robert Shaw 22 Claims, 8 Drawing Figs. [52] U.S.Cl. 101/1, ABSTRACT; ratus for high-speed printing in which a 101/1145346/75 perforated insulating material is provided with inner elec- [51] Int.Cl. ..G01d 15/18 nodes within each perforation to initiate ionization f a gas [50] Field of Search l0l/ l therein i response to an electrical signal, the gas being main- (ESDX 129; 346/75 tained in the ionized state thereafter by an electric potential [56] Ref "n Ct d connected between outer electrodes. At least one end of the e ces I e perforations is open thereby to allow the ionized gas to emit UNITED STATES PATENTS therefrom and to impinge upon a web in a determined fashion 2,737,882 3/1956 Early et a1 101/1X to imprint a pattern upon the web.

{I 2 4| 5 O O O O O O O o O O O O Q Q C) O O C) O O 0 IO 2 o o c o o o o o o o n- 1 l A i l l 6 e 1 v I HIGH-SPEED PRINTER EMPLOYING A GAS DISCHARGE MATRIX The present invention relates to printers and, more particularly, to printers employing a gaseous discharge matrix wherein the pattern of discharge can be programed to enable a message to be imprinted upon a web in response to signals from, for example, a digital computer.

In an application for Letters Patent entitled Ion Beam Printer, filed herewith by the present inventor, there is described printer apparatus using modulated ion beams of large or small, single or multiatomic ions to impress a message on a web. In the present invention the content of the message is effected by programing a multiperforation matrix and impressing the message thereby obtained upon a web.

In computers now developed high-speed solid state circuitry has drastically reduced the time required for computer calculations. However, the printing art has not kept pace, with the result that calculations that may take hours or minutes to per form may take days to print. The apparatus herein described is adapted to provide printout at a rate substantially equal to the rate of modern digital computers.

Accordingly, an object of the invention is to provide highspeed printout apparatus adapted to enable printing at a rate substantially equal to the output of modern computers.

Another object is to provide such apparatus in the form of a gaseous discharge matrix adapted simultaneously to print a line or a page, as required, in response to signals from a computer, but of more general utility, as well.

Other and still further objects will become evident upon reference to the description to follow and will be particularly pointed out in the appended claims.

By the way of summary, however, the objects of the invention are attained in a high-speed printer employing a gas discharge matrix having first and second electrode means separated by a perforated insulating medium having spaced electrodes within the perforations thereof. The first and second electrode means are adapted to receive an electric potential therebetween, and the spaced electrodes are adapted to receive an electric potential therebetween to ionize a gas within the perforations, the gas being thereafter maintained in the ionized state by the electric potential between the first and second electrode means.

The invention will now be discussed with reference to the accompanying drawing in which:

FIG. 1 is a schematic representation of a gas discharge matrix comprising a perforated insulating material sandwiched between outer, upper and lower, electrodes;

FIG. 2 is a fragmentary view, on an enlarged scale, of a portion of the matrix of FIG. 1 to show in detail the outline of one perforation with a pair of closely spaced inner electrodes;

FIG. 3 is a view taken upon the line 3-3 in FIG. 2 looking in the direction of the arrows;

FIG. 4 is a partial side view showing the matrix of FIG. 1 with a web adapted to travel adjacent the upper major surface of the insulating material and between the two outer electrode surfaces;

FIG. 5 is similar to FIG. 4 except the web, which is conductive in this instance, acts as the upper electrode surface;

FIG. 6 is similar to FIG. 4 except the web, which is electrically slightly conductive in this instance, is in electrical contact with the upper electrode surface;

FIG. 7 is a schematic representation of a printout arrangement including a developer; and

FIG. 8 is a fragmentary plan view of the matrix of FIG. 1 showing a group of 35 perforations, 14 of which are energized to form the letter F.

Referring now to FIG. 1 a gas discharge matrix for a highspeed printer is shown at 1 comprising first and second parallely disposed electrodes shown at 2 and 3, respectively, separated by a perforated insulating medium 4. A pair of spaced electrodes as, for example, the electrodes shown at A and B in FIG. 2 within each of the perforations or cavities 5 of the matrix are adapted to ionize a gas (which can be air) therein upon response to an electric signal from a signal source 14 connected therebetween. In FIG. 7 the electrodes A are shown connected serially together, and the electrodes B, designated B B B B etc., are individually energized. Thus, the electrodes A can be connected to one side of a source of signals as a common input and the electrodes B can be individually electrically energized in some detemiined pattern. For example, in FIG. 8 35 perforations 5 form a unit or group and by appropriately energizing the required electrodes A and B the letter F, as shown, can be formed. An electric potential 6 connected between the first and second electrodes maintains the gas in the ionized state once ionization has been initiated.

The matrix 1 can be made up of a plurality of groups of perforations or cavities 5, each of which groups can form any particular letter, number, or other configuration in response to signals applied to the electrodes A and B. In this manner words or other forms of communication can be formed in the matrix and can be impressed upon a web 7 in a manner now to be explained. The web 7 as shown in FIG. 7 is adapted to travel parallel to the upper major surface (shown at 4 in FIG. 1) of the gas discharge matrix 1 at some velocity U. In the illustrated embodiment as best shown in FIG. 2, the second or lower electrode 3 is solid and the first or upper electrode 2 is open at 2' which is an aperture preferably having slightly smaller cross dimensions than the cross dimensions of the perforation 5. Thus, any ionized gas within a perforation 5 will expand as a result of the heat generated by the passage of an electric current through the gas and will explode upward within the perforation (which parallelly oriented orthogonal to the major surface 4') through the aperture 2' in the electrode to strike the web 7. Since it is possible to energize any or all of the electrodes A and B in as short a time as one to ten microseconds, a message can be passed to the matrix in that short time, and the message can be impressed upon the web 7 over an area equal to the major surface 4'. The time for impressing the messageis so short that it is not even necessary to stop the web 7. For example, the source of electric potential 6 shown to be a dc. source in FIG. 1 can be a variable frequency a.c. source, as shown at 6' in FIG. 7, adjusted to provide a voltage across the first and second electrodes only at a time when the web is in a particular position relative to the matrix. Thus, the electrodes 2 and 3 can be energized at an appropriate time and shortly thereafter or simultaneously the electrodes A and B can be energized in the desired pattern to provide a message configuration in the matrix 1. The message can be transferred to the web 7, as previously discussed, and all the electrodes can thereafter be reduced to zero potential although the potential across the first and second electrodes may be held longer than the potential across the inner electrodes A and B.

The web can be paper, treated or untreated, or some other material. The impressions on the web can be effected by heat from ionized gas and for this purpose the paper may be treated with a heat sensitive coating such as a thin white wax or other coating over a dark surface as dyed paper. Or the web can be a highly insulating material which will retain the ions of the ionized gas at discrete locations to provide the message symbols which are made visible by passing the web 7 in FIG. 7 through a developer 8 where a dry powder (as carbon or almost any dry powder paint pigment) or a liquid containing dispersed pigment is applied to the electrically charged regions by spray, aerosol, or other application means. In this case the web must be highly insulating to prevent dispersal of charges from the charged regions.

As mentioned, the web may be a treated paper. By way of example, a paper web may have a coating of sodium or potassium ferrocyanide, and the developer may provide a mist of tannic acid to produce an image. Other combinations include ferric chloride and sodium ferrocyanide, ferric chloride and tannic acid. Other materials including plastic sheets and cloths, as well as paper, may be used to form a web.

The foregoing explanation concerned apparatus having an upper electrode 2 with an opening 2 therein. In the embodiments of FIGS. 4 and 6, the upper electrode, designated 2", is solid. The web 7 in FIG. 4 is made of an insulating material, as before, and high-energy ionized gases from the perforations 5 pass upward toward the electrode 2" but are intercepted by the web 7 to provide an impression, as before. In FIG. 6 the web shown at 7 is slightly conductive and is placed in electrical contact with the upper electrode 2". In this instance marks upon the web are effected by charring the web surface. In FIG. 5 the web designated 7" is made of a conductive material; and, in this instance, it is also the upper electrode. Again, marks thereon are effected by the ionized gas which chars a major surface thereof.

The matrix may be fabricated using sandwich construction wherein the lower electrode 3 is applied to one surface of a sheet of perforated insulating material such as glass or ceramic, and the electrodes B are applied to the other surface. The upper electrode 2 and electrodes A may be applied to opposite sides of a further insulating sheet, and the sheets may be combined (with a central insulating sheet) with the perforations registered to provide the composite perforations previously discussed. The electrodes A and B may be printed circuitry, or they may be single wires located within the perforations. It should be kept in mind, in this connection, that the electrodes A and B will generally be subjected to very short pulse of electric potential whereas the outer electrodes 2 and 3 will generally be energized for a much longer period. The distance separation between the outer electrodes 2 and 3 is typically .1 to .3 cm. whereas the separation between the inner electrodes A and B is typically .01 to .05 cm. The voltage between the outer electrodes 2 and 3 may be of the order of 500 to 1000 volts, and a similar signal voltage may be applied between inner electrodes A and B. The bias voltage supplied by the dc. source 6 may be disconnected by a switch 10 timed to open or close the circuit at times determined by the position of the web 7 or in response to some other parameter, as needed, or the source of potential to the outer electrodes 2 and 3 may be the a.c. source 6 in which event the ionized gas in the matrix will extinguish when the alternating potential drops below some predetermined value. Programing of the matrix can be effected using computer principles well known to persons in the art, and the signal source 14 can be the output of the computer or a potential source connected to the computer output. The web can be driven along a path parallel to the upper surface of the matrix by a drive 13, passing from a feed roll 11 to a takeup roll 12. The lower major surface of the web 7 thus travels parallel to the upper major surface 4' of the matrix and is preferably separated by about 0.05 to 1.0 millimeters therefrom. The environmental gas in the matrix may be air at ambient temperature and pressure, as mentioned, but other gases in a controlled atmosphere including, for example, nitrogen, argon, carbon dioxide, and other gases may be used, as well.

Modifications of the invention as described herein, including the provision of other chemicals for treating the web and developing images thereon, in addition to the chemicals herein disclosed, will occur to those skilled in the art, and all such modifications are considered to fall within the spirit and scope of the invention as defined in the appended claims.

Iclaim:

l. A highspeed printer employing a gas discharge matrix comprising, in combination, first and second electrode means, a transversely perforated insulating medium between the first and second electrode means having closely spaced electrodes within the perforations thereof, the first and second electrode means being adapted to receive an electric potential therebetween, the closely spaced electrodes being adapted tol receive an electric potential therebetween to initiate ionization of a gas within the perforations, the gas being thereafter maintained in the ionized state when an electric potential is simultaneously applied between the electrodes of the first and second electrode means.

2. Apparatus as claimed in claim 1 in which one of said first and second electrodes is a conductive web, one major surface of which is impressed by the ionized gases.

3. Apparatus as claimed in claim 1 and having a web adapted to pass between the insulating medium and at least one of the first and second electrode means.

4. A matrix as claimed in claim 1 in which the electrodes of the first and second electrode means are separated a substantially greater distance than the separation between the inner electrodes.

5. A matrix as claimed in claim 1 in which the insulating medium is a sheet of insulating material which contains a plurality of perforations extending from the upper surface to the lower surface thereof and a pair of inner closely spaced electrodes within each perforation, the electrodes of the first and second electrode means being disposed respectively at the upper and lower surfaces of the insulating sheet and spaced thereby to provide substantially greater distance therebetween than the separation between the inner electrodes.

6. A matrix as claimed in claim 5 in which the first electrodes means contains a plurality of apertures, the apertures thereof being positioned to register with corresponding perforations in the insulating medium and having slightly smaller cross dimensions than the cross dimensions of the perforations.

7. A matrix as claimed in claim 6 in which each electrode of the electrode pairs in connected to a source of electric signals, the source being connected to apply an electric potential across the electrodes of the electrode pairs in a pattern.

8. Apparatus as claimed in claim 7 and having a web positioned adjacent the first electrode, the plane of the web being disposed substantially parallel to the plane of the first electrode, a surface of the web being close enough to the apertures in the first electrode to be affected by gaseous discharge from said apertures effected by ionization of the gas therein, the discharge being effected in said pattern in response to signals from said source, the perforations being oriented substantially orthogonal to the surface of the web and the first and second electrode means being separated along the orthogonal direction.

9. Apparatus as claimed in claim 8 in which the source of electric signals is an electric potential source and in which the first and second electrode means are connected to a further source of electric potential, said gaseous discharge being the sole means by which the web is impressed.

10. Apparatus as claimed in claim 8 in which the insulating medium is a laminated structure comprising a central insulating sheet positioned between electrodes of the inner electrode pairs and two outer insulating sheets one adjacent each electrode of the inner electrode pairs and between said each electrode and the corresponding electrode surface.

11. Apparatus as claimed in claim 10 in which the electrodes of the electrode pairs are in the form of printed circuits located upon the surfaces of said central insulating sheet, one of the electrodes of each of the inner electrode pairs being located on one surface of the sheet and the other electrode of each of the inner electrode pairs being located on the other surface of the sheet.

12. Apparatus as claimed in claim 11 in which the apertures in the first electrode means are slightly smaller than the corresponding perforations in the insulating sheet, and the electrode pairs comprise a plurality of perforated electrodes disposed to register with corresponding perforations in the insulating medium.

13. Apparatus as claimed in claim 12 in which means is provided to drive the web along a path substantially parallel to the surface of the first electrode, thereby to transport the pattern from the region of the first electrode surface.

14. A matrix as claimed in claim 5 in which the separation between the electrode surfaces in .l to .3 cm. and the separation between the electrodes of the electrode pairs is about .01 to .05 cm.

15. A matrix as claimed in claim 14 in which the gas within the perforations is air.

16. A matrix as claimed in claim 1 in which the first electrode means is apertured, the apertures thereof being positioned to register with corresponding perforations in the insulating medium.

17. Apparatus as claimed in claim 16 having a web positioned adjacent the first electrode, the plane of the web being disposed substantially parallel to the plane of the first electrode, a surface of the web being close enough to the apertures in the first electrode to be affected by gaseous discharge from the apertures effected by ionization of the gas within the perforations.

18. Apparatus as claimed in claim 17 in which means is provided to drive the web along a path substantially parallel to the surface of the first electrode.

19. A high-speed printer employing a gas discharged matrix having, in combination, a matrix comprising a plurality of gascontaining cavities open at one end, electrode means within the cavities to receive electric potential to ionize the gas therein, a web positioned immediately adjacent the open ends of the cavities to be impressed by high energy gas ejected therefrom as a result of the heat generated by the passage of electric current through the gas, said electrode means comprising a pair of closely spaced electrodes within the cavities and connected to receive electric potential to initiate ionization, and further electrodes, said further electrodes being spaced much farther apart than the electrodes of the electrode pair and connected to receive electric potential to maintain the gas in the ionized state and to spread ionization throughout the cavities within which ionization is initiated.

20. A high-speed printer employing a gas discharge matrix having, in combination, a matrix comprising a plurality of gasfilled cavities each open at one end, electrode means comprising a pair of gas immersed closely spaced electrodes within each of the cavities and connected to a source of electric signals to initiate ionization in a pattern and further electrodes disposed in planes spaced much farther apart than the electrodes of the electrode pairs and connected to an electric potential source to produce ionization throughout the cavities within which ionization is initiated, one of the further electrodes containing apertures positioned to register with the cavities to allow emission of ionized gases from each of the cavities through the aperture associated therewith, and a web positioned immediately adjacent said apertures to be affected by high-energy gas ejected therefrom as a result of the heat generated by the passage of electric current through the gas, the web being positioned to travel adjacent to and substantially parallel to the apertured further electrode, a surface of the web being close enough to the apertures to be impressed by gaseous discharge from said apertures effected by ionization of the gas therein, the discharge being effected in said pattern in response to signals from the signal source.

21. A printer as claimed in claim 20 in which the cross dimensions of each aperture are slightly smaller than the cross dimensions of the cavity associated therewith.

22. A high-speed printer employing a gas discharge matrix having, in combination, a matrix comprising a plurality of solely gas-containing cavities each open at one end, electrode means comprising a pair of closely spaced electrodes disposed within the gas of each of the cavities and connected to a source of electric signals to initiate ionization of the gas in particular cavities in a pattern and further electrodes disposed in planes spaced much farther apart than the electrodes of the electrode pairs and connected to an electric potential source to maintain the gas in the ionized state and to spread ionization throughout the cavities within which ionization is initiated, a web positioned adjacent the open ends of the cavities to be impressed by high energy gas ejected therefrom as a result of the heat generated by the passage of electric current through the gas, a surface of the web being close enough to said open ends to be affected by gaseous discharge from the openings effected by ionization of the gas therein, the discharge being effected in said pattern in response to signals from said source. 

